Shine-Through Luminescent Wood Membranes

Thanks to its optical anisotropy and mechanical properties, luminescent wood is a promising material for indoor lighting applications. However, state-of-art approaches make use of potentially toxic fluorophores and of non-biodegradable...

Benzene and NOx photocatalytic assisted removal using indoor lighting conditions

Modern life-style is creating an indoor generation: human beings spend approximately 90% of their time indoors, almost 70% of which is at home – this trend is now exacerbated by the lockdowns/restrictions imposed due to the COVID-19 pandemic. That large amount of time spent indoors may have negative consequences on health and well-being. Indeed, poor indoor air quality is linked to a condition known as sick building syndrome. Therefore, breathing the freshest air possible it is of outmost importance. Still, due to reduced ventilation rates, indoor air quality can be considerably worse than outdoor. HVAC, air filtration systems and a well-ventilated space are a partial answer. However, these approaches involve only a physical removal. Photocatalytic mineralisation of pollutants into non-hazardous, or at least less dangerous compounds, is a more viable solution for their removal. Titanium dioxide, the archetype photocatalytic material, needs UVA light to be “activated”. However, modern household light emitting diode lamps irradiate only in the visible region of the solar spectrum. In this short-communication, we show that the surface of titanium dioxide nanoparticles modified with copper oxide(s) and graphene shows promise as a viable way to remove gaseous pollutants (benzene and NOx) by using a common light emitting diode bulb, mimicking real indoor lighting conditions. Titanium dioxide, modified with 1 mol% CuxO and 1 wt% graphene, proved to have a stable photocatalytic degradation rate, three times higher than that of unmodified titania. Materials produced in this research work are thus strong candidates for offering a safer indoor environment.

Indoor temperature, humidity and illumination control system based on Android

The temperature, humidity and illumination control system designed in this paper is based on Android platform. It is controlled by connecting the mobile phone wifi with the single chip microcomputer, and uploaded to the mobile phone client through wifi serial port technology. Users can collect indoor temperature and humidity data and illumination data through sensors. Through the mobile phone client to control the LED lights and relay switches of household appliances, such as the control of air conditioning, and finally achieve the goal of adjusting indoor lighting and controlling the on-off of household appliances.

The Calculated Circadian Effects of Light Exposure from Commuting

Light entrains human circadian rhythms, but increased time spent indoors and decreased daylight exposure may disrupt human circadian regulation and cause health problems. Much research is focused on improving indoor lighting conditions to minimize the adverse circadian impact of electric lights, and few studies investigate the circadian impact of daylight during the incidental time that people spend outdoors. For instance, when people commute from home to work, they are exposed to daylight. The purpose of this study is to investigate daylight’s impact on commuters’ circadian rhythms. Measurements of the illuminance and the spectral irradiance distribution (SID) of daylight were taken for three modes of commuting: driving, riding on trains, and walking; and under different weather conditions, on different days, and at different locations throughout the summer and autumn in the Sydney metropolitan region in Australia. With the SID data, three metrics were calculated to estimate the circadian impacts: α-opic irradiance, circadian stimulus (CS), and equivalent melanopic lux (EML). The results suggest that driving or walking on sunny or cloudy days and riding trains on sunny days are beneficial for the commuters’ circadian synchronization.

A simple design of uniform LED illumination using catadioptric collimator and freeform lenslet array

We introduce a compact lenslet array principle that takes advantage of freeform optics to deploy a light distributor, beneficial for highly efficient, inexpensive, low energy consumption light-emitting diode (LED) lighting system. We outline here a simple strategy for designing the freeform lens that makes use of an array of the identical plano-convex lenslet. The light is redistributed from such lenslet, hinging on the principle of optical path length conservation, and then delivered to the receiver plane. The superimposing of such illumination area from every lenslet occurs on the receiver plane, in which the non-uniform illumination area located in the boundary should have the same dimension as the size of the freeform lenslet array. Such an area, insofar, is negligible due to their small size, which is the crux of our design, representing a large departure from the former implementations. Based on simulations that assess light performance, the proposed design exhibited the compatibility for multiple radiation geometries and off-axis lighting without concern for the initial radiation pattern of the source. As simulated, the LED light source integrated with such proposed freeform lenslet array revealed high luminous efficiency and uniformity within the illumination area of interest were above 70% and 85%, respectively. Such novel design was then experimentally demonstrated to possess a uniformity of 75% at hand, which was close to the simulation results. Also, proposed indoor lighting was implemented in comparison with the commercial LED downlight and LED panel, whereby the energy consumption, number of luminaires and illumination performance were assessed to show the advantage of our simplified model.

VALIDATION OF SPECTRAL SIMULATION TOOLS FOR THE PREDICTION OF INDOOR ELECTRIC LIGHT EXPOSURE

As the interest in design applications related to responses to light beyond vision is growing, two simulation tools, ALFA and Lark, have been developed to incorporate spectral characteristics of light in the evaluation of indoor lighting conditions. The spectral characteristics of light are of particular relevance when studying ipRGC-influenced responses. This paper aims to assess the reliability of these tools in predicting indoor spectral irradiance specifically from electric lighting. Spectral irradiance was measured under three indoor electric lighting scenarios and compared against spectral irradiance simulated in ALFA and Lark. While the outcomes of the study tend to show that ALFA is both more accurate and faster, rather large errors were found for spectral irradiance (-28.6% to 33.4%). In comparison to a prior study focusing on daylighting, these results seem to indicate that spectral simulations of electrically lit scenes are generally less accurate than those of daylit scenes with these tools.

PERCEIVED CHROMA AND HUE CHANGES OF COLOURS AT HIGH ILLUMINANCE LEVELS DUE TO HUNT EFFECT

The purpose of this study is to quantify the Hunt Effect in a range from indoor lighting levels to outdoor daylight levels so that a perception model of Hunt Effect for lighting can be developed with outdoor daylight as the reference. Our previous study experimentally quantified the perceived chroma changes due to the Hunt Effect at 100 lx and 1000 lx. To extend this to light levels closer to outdoor daylight, a vision experiment was conducted at ≈1000 lx and ≈6000 lx for red, green, yellow, and blue patches. A reference patch on one side of a double booth at 1000 lx was compared to a set of 20 test patches on the other side of the booth at ≈6000 lx using haploscopic view condition. Results showed that the perceived chroma changes are much smaller and insignificant compared to the results between 100 lx and 1000 lx found in our previous study.

A GENERIC GLARE SENSATION MODEL BASED ON THE HUMAN VISUAL SYSTEM

Conventional discomfort glare measures are based on glare source properties like luminous intensity or luminance and typically are valid only to specific situations and to specific types of light sources. For instance, the Unified Glare Rating (UGR) is intended for indoor lighting conditions with medium-sized glare sources, whereas another class of discomfort glare measures is specifically devoted to car headlamps. Recently, CIE TC 3-57 started with the aim to develop a more generic glare sensation model based on the human visual system. We present an example of such a model, including a detailed description of aspects like pupil constriction, retinal image formation, photoreceptor response and adaptation, receptive field-type filtering in the retina, and neural spatial summation. The linear correlation of the model to UGR in an indoor setting, and to subjective glare responses in an outdoor-like setting indicate that the human-visual-system-based model may indeed be considered generic.

Development of a light control system using an optical aerial information transmission system

The inefficiency of the use of electric energy for indoor lighting is shown. The necessity of modernization of lighting control systems in the workplace area is justified. The method of automatic control and adjustment of illumination of workplaces and zones where it is necessary is offered. A control system has been developed, which is integrated into the air optical information transmission system (Internet). The simulation of the system operation is carried out, its parameters are calculated. The main characteristics are measured.